Search results for "porter"
showing 10 items of 920 documents
Cationic amino acid transport across the blood-brain barrier is mediated exclusively by system y+.
2006
Cationic amino acid (CAA) transport is brought about by two families of proteins that are found in various tissues: Cat (CAA transporter), referred to as system y+, and Bat [broad-scope amino acid (AA) transporter], which comprises systems b0,+, B0,+, and y+L. CAA traverse the blood-brain barrier (BBB), but experiments done in vivo have only been able to examine the BBB from the luminal (blood-facing) side. In the present study, plasma membranes isolated from bovine brain microvessels were used to identify and characterize the CAA transporter(s) on both sides of the BBB. From these studies, it was concluded that system y+was the only transporter present, with a prevalence of activity on the…
Transport of C(4)-dicarboxylates in Wolinella succinogenes.
2000
ABSTRACT C 4 -dicarboxylate transport is a prerequisite for anaerobic respiration with fumarate in Wolinella succinogenes , since the substrate site of fumarate reductase is oriented towards the cytoplasmic side of the membrane. W. succinogenes was found to transport C 4 -dicarboxylates (fumarate, succinate, malate, and aspartate) across the cytoplasmic membrane by antiport and uniport mechanisms. The electrogenic uniport resulted in dicarboxylate accumulation driven by anaerobic respiration. The molar ratio of internal to external dicarboxylate concentration was up to 10 3 . The dicarboxylate antiport was either electrogenic or electroneutral. The electroneutral antiport required the prese…
Intralaboratory validation of four in vitro assays for the prediction of the skin sensitizing potential of chemicals
2011
Abstract Allergic contact dermatitis is induced by repeated skin contact with an allergen. Assessment of the skin sensitizing potential of chemicals, agrochemicals, and especially cosmetic ingredients is currently performed with the use of animals. Animal welfare and EU legislation demand animal-free alternatives reflected in a testing and marketing ban for cosmetic ingredients beginning in 2013. The underlying mechanisms of induction and elicitation of skin sensitization are complex and a chemical needs to comply several properties being skin sensitizing. To account for the multitude of events in the induction of skin sensitization an in vitro test system will consist of a battery of vario…
Sterically geared tris-thioureas; transmembrane chloride transporters with unusual activity and accessibility
2015
Tris-N-arylthioureas derived in one step from 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene are remarkably effective anion carriers. With optimised aryl substituents their activities come close to the best currently known, suggesting that they might find use as readily available standards in anion transport research.
Eight-Membered Rings With Two Heteroatoms 1,3
2022
Eight-membered rings with two heteroatoms in a 1,3-relationship, namely 1,3-diazocine, 2H-1,3-oxazocine, 2H-1,3-thiazocine, 4H-1,3-dioxocin, 4H-1,3-oxathiocin, and 4H-1,3-dithiocin, are discussed in this chapter, that covers the literature from 2007 to October 2020 (SciFindern search) and reports the chemistry of uncondensed derivatives, heterocines fused to carbocycles and heterocycles, as well as bridged heterocines. Among eight-membered 1,3-diheterocines, 1,3-diazocines and 1,3-oxazocines are the two largest classes, based on the number of publications, mostly due to the studies of the synthesis of these cyclic systems, their pharmacological properties and/or their important industrial a…
Preíndices que determinan la anticipación del portero de hockey hierba ante un golpeo de revés
2015
La tesis se encuadra en el estudio de los elementos perceptivos y atencionales que modulan la captación de información, aspecto clave para la toma de decisión y posterior acción motriz que conforman el modelo de procesamiento de la información (Marteniuk, 1976). Para la correcta ejecución de muchas de las acciones que se realizan en la actividad deportiva, la capacidad de extraer del entorno la información más relevante y procesarla adecuadamente es esencial. Esta capacidad se torna más relevante aún en los deportes de predominio de situaciones abiertas, como las que caracterizan a los deportes de equipo, donde la dinámica del entorno en el que se desarrollan las acciones genera gran cantid…
TAP off - tumors on
1997
Abstract The molecular characterization of T-cell-defined tumor-associated antigens has provided targets for cell-mediated immunotherapy for malignant diseases. The success of this strategy is negatively influenced by structural and functional abnormalities of major histocompatibility complex (MHC) class I molecules, which provide tumor cells with resistance to T-cell-mediated immune recognition. This article reviews the physiology of the MHC class I processing machinery and describes the deficiencies of this pathway in malignant cells.
DctA- and Dcu-independent transport of succinate in Escherichia coli : contribution of diffusion and of alternative carriers
2001
Quintuple mutants of Escherichia coli deficient in the C4-dicarboxylate carriers of aerobic and anaerobic metabolism (DctA, DcuA, DcuB, DcuC, and the DcuC homolog DcuD, or the citrate/succinate antiporter CitT) showed only poor growth on succinate (or other C4-dicarboxylates) under oxic conditions. At acidic pH (pH 6) the mutants regained aerobic growth on succinate, but not on fumarate. Succinate uptake by the mutants could not be saturated at physiological succinate concentrations (≤5 mM), in contrast to the wild-type, which had a K m for succinate of 50 µM and a V max of 35 U/g dry weight at pH 6. At high substrate concentrations, the mutants showed transport activities (32 U/g dry weigh…
The Fumarate/Succinate Antiporter DcuB of Escherichia coli Is a Bifunctional Protein with Sites for Regulation of DcuS-dependent Gene Expression
2008
DcuB of Escherichia coli catalyzes C4-dicarboxylate/succinate antiport during growth by fumarate respiration. The expression of genes of fumarate respiration, including the genes for DcuB (dcuB) and fumarate reductase (frdABCD) is transcriptionally activated by C4-dicarboxylates via the DcuS-DcuR two-component system, comprising the sensor kinase DcuS, which contains a periplasmic sensing domain for C4-dicarboxylates. Deletion or inactivation of dcuB caused constitutive expression of DcuS-regulated genes in the absence of C4-dicarboxylates. The effect was specific for DcuB and not observed after inactivation of the homologous DcuA or the more distantly related DcuC transporter. Random and s…
Interaction of theEscherichia colitransporter DctA with the sensor kinase DcuS: presence of functional DctA/DcuS sensor units
2012
The aerobic Escherichia coli C(4) -dicarboxylate transporter DctA and the anaerobic fumarate/succinate antiporter DcuB function as obligate co-sensors of the fumarate responsive sensor kinase DcuS under aerobic or anaerobic conditions respectively. Overproduction under anaerobic conditions allowed DctA to replace DcuB in co-sensing, indicating their functional equivalence in this capacity. In vivo interaction studies between DctA and DcuS using FRET or a bacterial two-hybrid system (BACTH) demonstrated their interaction. DctA-YFP bound to an affinity column and was able to retain DcuS. DctA shows substantial sequence and secondary structure conservation to Glt(Ph), the Na(+)/glutamate sympo…